2. Based on our previous research and preliminary data that non-Th2 asthma can be further divided in Th17 asthma and Th1+Th2 asthma; besides these, a fourth group without Th2, Th17 or Th1 characteristics also exist. The investigators hypothesize that the epithelial cell cytokine, TSLP, can be increased as an early marker of airway inflammation in this latter group.